Systems and methods for applying reduced negative pressure therapy

ABSTRACT

Embodiments of a negative pressure wound therapy systems and methods for operating the systems are disclosed. In some embodiments, a system includes a pump assembly, canister, and a wound dressing configured to be positioned over a wound. The pump assembly, canister, and the wound dressing can be fluidically connected to facilitate delivery of negative pressure to a wound. The system can be configured to efficiently deliver negative pressure in continuous and intermittent modes. The system can also be configured to gradually ramp up and down to set pressure values. The system can also be configured to detect and indicate presence of certain conditions, such as low pressure, high pressure, leak, canister full, and the like. Detection and indication of the presence of at least some of these conditions can be enabled and disabled.

BACKGROUND Field

Embodiments of the present disclosure relate to methods and apparatusesfor dressing and treating a wound with reduced pressure therapy ortopical negative pressure (TNP) therapy. In particular, but withoutlimitation, embodiments disclosed herein relate to negative pressuretherapy devices, methods for controlling the operation of TNP systems,and methods of using TMP systems.

Description of the Related Art

Many different types of wound dressings are known for aiding in thehealing process of a human or animal. These different types of wounddressings include many different types of materials and layers, forexample, gauze, pads, foam pads or multi-layer wound dressings. Topicalnegative pressure (TNP) therapy, sometimes referred to as vacuumassisted closure, negative pressure wound therapy, or reduced pressurewound therapy, is widely recognized as a beneficial mechanism forimproving the healing rate of a wound. Such therapy is applicable to abroad range of wounds such as incisional wounds, open wounds andabdominal wounds or the like.

TNP therapy assists in the closure and healing of wounds by reducingtissue oedema, encouraging blood flow, stimulating the formation ofgranulation tissue, removing excess exudates and may reduce bacterialload and, thus, infection to the wound. Furthermore, TNP therapy permitsless outside disturbance of the wound and promotes more rapid healing.

SUMMARY

In some embodiments, an apparatus for applying negative pressure therapyto a wound includes a source of negative pressure configured to be influidic communication with a wound dressing and configured to aspiratefluid from the wound, a pressure sensor configured to measure pressureunder the wound dressing, and a controller configured to operate thesource of negative pressure to reach a pressure setting under the wounddressing. The controller can be further configured to determine apressure difference between current pressure under the wound dressingmeasured by the pressure sensor and the pressure setting, wherein thepressure setting is more positive than the current pressure under thewound dressing, and based on the pressure difference and a compressionsetting, operate the source of negative pressure to attain the pressuresetting under the wound dressing.

In some embodiments, the apparatus of the preceding paragraph caninclude one or more of the following features. The controller can befurther configured to determine an intermediate pressure setting that ismore positive than the current pressure and more negative than thepressure setting and operate the source of negative pressure to attainthe intermediate pressure setting under the wound dressing. Thecontroller can be further configured to determine a pressure incrementbased on the compression setting and set the intermediate pressuresetting to a sum of the current pressure and the pressure increment. Thecontroller can be further configured to in response to determining thatthe current intermediate pressure setting has been achieved under thewound dressing, update the intermediate pressure setting to be equal toa sum of previous intermediate pressure setting and the pressureincrement. The controller can be further configured to in response todetermining that the current intermediate pressure setting has beenachieved under the wound dressing, redetermine the pressure incrementand update the intermediate pressure setting to be equal to a sum ofprevious intermediate pressure setting and the updated pressureincrement. The controller can be further configured to turn off thesource of negative pressure for a duration of time, the duration of timebased on the compression setting. The compression setting can beselected by a user.

In some embodiments, a method of operating a negative pressure apparatusincludes measuring pressure under a wound dressing configured to bepositioned over a wound, determining a pressure difference betweencurrent pressure under the wound dressing and a pressure setting,wherein the pressure setting is more positive than the current pressureunder the wound dressing, and based on the pressure difference and acompression setting, providing negative pressure to the wound dressingto attain the pressure setting under the wound dressing.

In some embodiments, the method of the preceding paragraph can includeone or more of the following features. The method can further includedetermining an intermediate pressure setting that is more positive thanthe current pressure and more negative than the pressure setting andproviding negative pressure to the wound dressing to attain theintermediate pressure setting under the wound dressing. The method canfurther include determining a pressure increment based on thecompression setting and setting the intermediate pressure setting to asum of the current pressure and the pressure increment. The method canfurther include in response to determining that the current intermediatepressure setting has been achieved under the wound dressing, updatingthe intermediate pressure setting to be equal to a sum of previousintermediate pressure setting and the pressure increment. The method canfurther include in response to determining that the current intermediatepressure setting has been achieved under the wound dressing,redetermining the pressure increment and updating the intermediatepressure setting to be equal to a sum of previous intermediate pressuresetting and the updated pressure increment. The method can furtherinclude stopping provision of negative pressure to the wound for aduration of time, the duration of time based on the compression setting.The compression setting can be selected by a user.

In some embodiments, an apparatus for applying negative pressure therapyto a wound includes a source of negative pressure configured to be influidic communication with a wound dressing via a fluid flow path, thesource of negative pressure configured to aspirate fluid from the woundand a controller configured to operate the source of negative pressure.The controller can be further configured to deactivate detection of apresence of a condition in the fluid flow path, in response tooccurrence of an event, activate detection of the presence of thecondition in the fluid flow path, and in response to detecting thepresence of the condition in the fluid flow path, provide an indicationof the presence of the condition.

In some embodiments, the apparatus of the preceding paragraph caninclude one or more of the following features. The apparatus can includea canister positioned in the fluid flow path and configured to store atleast some of the aspirated fluid. The condition can include one of ablockage in the fluid flow path, a leak in the fluid flow path, lowpressure in the fluid flow path, high pressure in the fluid flow path,or a canister full. The controller can be further configured todeactivate the detection while the negative pressure source is activatedto provide a negative pressure level under the wound dressing. The eventcan include reaching a steady state pressure under the wound dressing.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described hereinafter,by way of example only, with reference to the accompanying drawings inwhich:

FIG. 1 illustrates a reduced pressure wound therapy system according tosome embodiments.

FIGS. 2A-2C illustrate a pump assembly and canister according to someembodiments.

FIG. 3 illustrates an electrical component schematic of a pump assemblyaccording to some embodiments.

FIG. 4 illustrates a firmware and/or software diagram according to someembodiments.

FIGS. 5A-5I illustrate graphical user interface screens according tosome embodiments.

FIGS. 6A-6G illustrate alarms screens according to some embodiments.

FIG. 7 illustrates a process of providing negative pressure woundtherapy according to some embodiments.

FIG. 8 illustrates pressure pulses according to some embodiments.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Overview

Embodiments disclosed herein relate to systems and methods of treating awound with reduced pressure. As is used herein, reduced or negativepressure levels, such as −X mmHg, represent pressure levels relative tonormal ambient atmospheric pressure, which can correspond to 760 mmHg(or 1 atm, 29.93 inHg, 101.325 kPa, 14.696 psi, etc.). Accordingly, anegative pressure value of −X mmHg reflects absolute pressure that is XmmHg below 760 mmHg or, in other words, an absolute pressure of (760−X)mmHg. In addition, negative pressure that is “less” or “smaller” than XmmHg corresponds to pressure that is closer to atmospheric pressure(e.g., −40 mmHg is less than −60 mmHg). Negative pressure that is “more”or “greater” than −X mmHg corresponds to pressure that is further fromatmospheric pressure (e.g., −80 mmHg is more than −60 mmHg). In someembodiments, local ambient atmospheric pressure is used as a referencepoint, and such local atmospheric pressure may not necessarily be, forexample, 760 mmHg.

Embodiments of the present invention are generally applicable to use intopical negative pressure (TNP) or reduced pressure therapy systems.Briefly, negative pressure wound therapy assists in the closure andhealing of many forms of “hard to heal” wounds by reducing tissueoedema, encouraging blood flow and granular tissue formation, and/orremoving excess exudate and can reduce bacterial load (and thusinfection risk). In addition, the therapy allows for less disturbance ofa wound leading to more rapid healing. TNP therapy systems can alsoassist in the healing of surgically closed wounds by removing fluid. Insome embodiments, TNP therapy helps to stabilize the tissue in theapposed position of closure. A further beneficial use of TNP therapy canbe found in grafts and flaps where removal of excess fluid is importantand close proximity of the graft to tissue is required in order toensure tissue viability.

Negative Pressure System

FIG. 1 illustrates an embodiment of a negative or reduced pressure woundtreatment (or TNP) system 100 comprising a wound filler 130 placedinside a wound cavity 110, the wound cavity sealed by a wound cover 120.The wound filler 130 in combination with the wound cover 120 can bereferred to as wound dressing. A single or multi lumen tube or conduit140 is connected the wound cover 120 with a pump assembly 150 configuredto supply reduced pressure. The wound cover 120 can be in fluidiccommunication with the wound cavity 110. In any of the systemembodiments disclosed herein, as in the embodiment illustrated in FIG.1, the pump assembly can be a canisterless pump assembly (meaning thatexudate is collected in the wound dressing or is transferred via tube140 for collection to another location). However, any of the pumpassembly embodiments disclosed herein can be configured to include orsupport a canister. Additionally, in any of the system embodimentsdisclosed herein, any of the pump assembly embodiments can be mounted toor supported by the dressing, or adjacent to the dressing. The woundfiller 130 can be any suitable type, such as hydrophilic or hydrophobicfoam, gauze, inflatable bag, and so on. The wound filler 130 can beconformable to the wound cavity 110 such that it substantially fills thecavity. The wound cover 120 can provide a substantially fluidimpermeable seal over the wound cavity 110. The wound cover 120 can havea top side and a bottom side, and the bottom side adhesively (or in anyother suitable manner) seals with wound cavity 110. The conduit 140 orlumen or any other conduit or lumen disclosed herein can be formed frompolyurethane, PVC, nylon, polyethylene, silicone, or any other suitablematerial.

Some embodiments of the wound cover 120 can have a port (not shown)configured to receive an end of the conduit 140. In other embodiments,the conduit 140 can otherwise pass through and/or under the wound cover120 to supply reduced pressure to the wound cavity 110 so as to maintaina desired level of reduced pressure in the wound cavity. The conduit 140can be any suitable article configured to provide at least asubstantially sealed fluid flow pathway between the pump assembly 150and the wound cover 120, so as to supply the reduced pressure providedby the pump assembly 150 to wound cavity 110.

The wound cover 120 and the wound filler 130 can be provided as a singlearticle or an integrated single unit. In some embodiments, no woundfiller is provided and the wound cover by itself may be considered thewound dressing. The wound dressing may then be connected, via theconduit 140, to a source of negative pressure, such as the pump assembly150. The pump assembly 150 can be miniaturized and portable, althoughlarger conventional pumps such can also be used.

The wound cover 120 can be located over a wound site to be treated. Thewound cover 120 can form a substantially sealed cavity or enclosure overthe wound site. In some embodiments, the wound cover 120 can beconfigured to have a film having a high water vapour permeability toenable the evaporation of surplus fluid, and can have a superabsorbingmaterial contained therein to safely absorb wound exudate. It will beappreciated that throughout this specification reference is made to awound. In this sense it is to be understood that the term wound is to bebroadly construed and encompasses open and closed wounds in which skinis torn, cut or punctured or where trauma causes a contusion, or anyother surficial or other conditions or imperfections on the skin of apatient or otherwise that benefit from reduced pressure treatment. Awound is thus broadly defined as any damaged region of tissue wherefluid may or may not be produced. Examples of such wounds include, butare not limited to, acute wounds, chronic wounds, surgical incisions andother incisions, subacute and dehisced wounds, traumatic wounds, flapsand skin grafts, lacerations, abrasions, contusions, burns, diabeticulcers, pressure ulcers, stoma, surgical wounds, trauma and venousulcers or the like. The components of the TNP system described hereincan be particularly suited for incisional wounds that exude a smallamount of wound exudate.

Some embodiments of the system are designed to operate without the useof an exudate canister. Some embodiments can be configured to support anexudate canister. In some embodiments, configuring the pump assembly 150and tubing 140 so that the tubing 140 can be quickly and easily removedfrom the pump assembly 150 can facilitate or improve the process ofdressing or pump changes, if necessary. Any of the pump embodimentsdisclosed herein can be configured to have any suitable connectionbetween the tubing and the pump.

In some embodiments, the pump assembly 150 can be configured to delivernegative pressure of approximately −80 mmHg, or between about −20 mmHgand −200 mmHg. Note that these pressures are relative to normal ambientatmospheric pressure thus, −200 mmHg would be about 560 mmHg inpractical terms. The pressure range can be between about −40 mmHg and−150 mmHg. Alternatively a pressure range of up to −75 mmHg, up to −80mmHg or over −80 mmHg can be used. Also a pressure range of below −75mmHg can be used. Alternatively a pressure range of over approximately−100 mmHg, or even 150 mmHg, can be supplied by the pump assembly 150.

In some embodiments, the pump assembly 150 is configured to providecontinuous or intermittent negative pressure therapy. Continuous therapycan be delivered at −25 mmHg, −40 mmHg, −50 mmHg, −60 mmHg, −70 mmHg,−80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180mmHg, −200 mmHg, or below −200 mmHg. Intermittent therapy can bedelivered between low and high negative pressure setpoints. Low setpointcan be set at 0 mmHg, −25 mmHg, −40 mmHg, −50 mmHg, −60 mmHg, −70 mmHg,−80 mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180mmHg, or below −180 mmHg. High setpoint can be set at −25 mmHg, −40mmHg, −50 mmHg, −60 mmHg, −70 mmHg, −80 mmHg, −90 mmHg, −100 mmHg, −120mmHg, −140 mmHg, −160 mmHg, −180 mmHg, −200 mmHg, or below −200 mmHg.During intermittent therapy, negative pressure at low setpoint can bedelivered for a first time duration, and upon expiration of the firsttime duration, negative pressure at high setpoint can be delivered for asecond time duration. Upon expiration of the second time duration,negative pressure at low setpoint can be delivered. The first and secondtime durations can be same or different values. The first and seconddurations can be selected from the following range: less than 2 minutes,2 minutes, 3 minutes, 4 minutes, 6 minutes, 8 minutes, 10 minutes, orgreater than 10 minutes. In some embodiments, switching between low andhigh setpoints and vice versa can be performed according to a stepwaveform, square waveform, sinusoidal waveform, and the like.

In operation, the wound filler 130 is inserted into the wound cavity 110and wound cover 120 is placed so as to seal the wound cavity 110. Thepump assembly 150 provides a source of a negative pressure to the woundcover 120, which is transmitted to the wound cavity 110 via the woundfiller 130. Fluid (e.g., wound exudate) is drawn through the conduit140, and can be stored in a canister. In some embodiments, fluid isabsorbed by the wound filler 130 or one or more absorbent layers (notshown).

Wound dressings that may be utilized with the pump assembly and otherembodiments of the present application include Renasys-F, Renasys-G,Renasys AB, and Pico Dressings available from Smith & Nephew. Furtherdescription of such wound dressings and other components of a negativepressure wound therapy system that may be used with the pump assemblyand other embodiments of the present application are found in U.S.Patent Publication Nos. 2011/0213287, 2011/0282309, 2012/0116334,2012/0136325, and 2013/0110058, which are incorporated by reference intheir entirety. In other embodiments, other suitable wound dressings canbe utilized.

Pump Assembly and Canister

FIG. 2A illustrates a front view 200A of a pump assembly 230 andcanister 220 according to some embodiments. As is illustrated, the pumpassembly 230 and the canister are connected, thereby forming a device.The pump assembly 230 comprises one or more indicators, such as visualindicator 202 configured to indicate alarms and visual indicator 204configured to indicate status of the TNT system. The indicators 202 and204 can be configured to alert a user, such as patient or medical careprovider, to a variety of operating and/or failure conditions of thesystem, including alerting the user to normal or proper operatingconditions, pump failure, power supplied to the pump or power failure,detection of a leak within the wound cover or flow pathway, suctionblockage, or any other similar or suitable conditions or combinationsthereof. The pump assembly 230 can comprise additional indicators. Thepump assembly can use a single indicator or multiple indicators. Anysuitable indicator can be used such as visual, audio, tactile indicator,and so on. The indicator 202 can be configured to signal alarmconditions, such as canister full, power low, conduit 140 disconnected,seal broken in the wound seal 120, and so on. The indicator 202 can beconfigured to display red flashing light to draw user's attention. Theindicator 204 can be configured to signal status of the TNP system, suchas therapy delivery is ok, leak detected, and so on. The indicator 204can be configured to display one or more different colors of light, suchas green, yellow, etc. For example, green light can be emitted when theTNP system is operating properly and yellow light can be emitted toindicate a warning.

The pump assembly 230 comprises a display or screen 206 mounted in arecess 208 formed in a case of the pump assembly. The display 206 can bea touch screen display. The display 206 can support playback ofaudiovisual (AV) content, such as instructional videos. As explainedbelow, the display 206 can be configured to render a number of screensor graphical user interfaces (GUIs) for configuring, controlling, andmonitoring the operation of the TNP system. The pump assembly 230comprises a gripping portion 210 formed in the case of the pumpassembly. The gripping portion 210 can be configured to assist the userto hold the pump assembly 230, such as during removal of the canister220. The canister 220 can be replaced with another canister, such aswhen the canister 220 has been filled with fluid.

The pump assembly 230 comprises one or more keys or buttons 212configured to allow the user to operate and monitor the operation of theTNP system. As is illustrated, there buttons 212 a, 212 b, and 212 c areincluded. Button 212 a can be configured as a power button to turnon/off the pump assembly 230. Button 212 b can be configured as aplay/pause button for the delivery of negative pressure therapy. Forexample, pressing the button 212 b can cause therapy to start, andpressing the button 212 b afterward can cause therapy to pause or end.Button 212 c can be configured to lock the display 206 and/or thebuttons 212. For instance, button 212 c can be pressed so that the userdoes not unintentionally alter the delivery of the therapy. Button 212 ccan be depressed to unlock the controls. In other embodiments,additional buttons can be used or one or more of the illustrated buttons212 a, 212 b, or 212 c can be omitted. Multiple key presses and/orsequences of key presses can be used to operate the pump assembly 230.

The pump assembly 230 includes one or more latch recesses 222 formed inthe cover. In the illustrated embodiment, two latch recesses 222 can beformed on the sides of the pump assembly 230. The latch recesses 222 canbe configured to allow attachment and detachment of the canister 220using one or more canister latches 221. The pump assembly 230 comprisesan air outlet 224 for allowing air removed from the wound cavity 110 toescape. Air entering the pump assembly can be passed through one or moresuitable filters, such as antibacterial filters. This can maintainreusability of the pump assembly. The pump assembly 230 includes one ormore strap mounts 226 for connecting a carry strap to the pump assembly230 or for attaching a cradle. In the illustrated embodiment, two strapmounts 226 can be formed on the sides of the pump assembly 230. In someembodiments, various of these features are omitted and/or variousadditional features are added to the pump assembly 230.

The canister 220 is configured to hold fluid (e.g., exudate) removedfrom the wound cavity 110. The canister 220 includes one or more latches221 for attaching the canister to the pump assembly 230. In theillustrated embodiment, the canister 220 comprises two latches 221 onthe sides of the canister. The exterior of the canister 220 can formedfrom frosted plastic so that the canister is substantially opaque andthe contents of the canister and substantially hidden from plain view.The canister 220 comprises a gripping portion 214 formed in a case ofthe canister. The gripping portion 214 can be configured to allow theuser to hold the pump assembly 220, such as during removal of thecanister from the apparatus 230. The canister 220 includes asubstantially transparent window 216, which can also include graduationsof volume. For example, the illustrated 300 mL canister 220 includesgraduations of 50 mL, 100 mL, 150 mL, 200 mL, 250 mL, and 300 mL. Otherembodiments of the canister can hold different volume of fluid and caninclude different graduation scale. For example, the canister can be an800 mL canister. The canister 220 comprises a tubing channel 218 forconnecting to the conduit 140. In some embodiments, various of thesefeatures, such as the gripping portion 214, are omitted and/or variousadditional features are added to the canister 220. Any of the disclosedcanisters may include or may omit a solidifier.

FIG. 2B illustrates a rear view 200B of the pump assembly 230 andcanister 220 according to some embodiments. The pump assembly 230comprises a speaker port 232 for producing sound. The pump assembly 230includes a filter access door 234 for accessing and replacing one ormore filters, such as antibacterial filters. The pump assembly 230comprises a gripping portion 236 formed in the case of the pumpassembly. The gripping portion 236 can be configured to allow the userto hold the pump assembly 230, such as during removal of the canister220. The pump assembly 230 includes one or more covers 238 configured toas screw covers and/or feet or protectors for placing the pump assembly230 on a surface. The covers 230 can be formed out of rubber, silicone,or any other suitable material. The pump assembly 230 comprises a powerjack 239 for charging and recharging an internal battery of the pumpassembly. The power jack 239 can be a direct current (DC) jack. In someembodiments, the pump assembly can comprise a disposable power source,such as batteries, so that no power jack is needed.

The canister 220 includes one or more feet 244 for placing the canisteron a surface. The feet 244 can be formed out of rubber, silicone, or anyother suitable material and can be angled at a suitable angle so thatthe canister 220 remains stable when placed on the surface. The canister220 comprises a tube mount relief 246 configured to allow one or moretubes to exit to the front of the device. The canister 220 includes astand or kickstand 248 for supporting the canister when it is placed ona surface. As explained below, the kickstand 248 can pivot between anopened and closed position. In closed position, the kickstand 248 can belatched to the canister 220. In some embodiments, the kickstand 248 canbe made out of opaque material, such as plastic. In other embodiments,the kickstand 248 can be made out of transparent material. The kickstand248 includes a gripping portion 242 formed in the kickstand. Thegripping portion 242 can be configured to allow the user to place thekickstand 248 in the closed position. The kickstand 248 comprises a hole249 to allow the user to place the kickstand in the open position. Thehole 249 can be sized to allow the user to extend the kickstand using afinger.

FIG. 2C illustrates a view 200C of the pump assembly 230 separated fromthe canister 220 according to some embodiments. The pump assembly 230includes a vacuum attachment, connector, or inlet 252 through which avacuum pump communicates negative pressure to the canister 220. The pumpassembly aspirates fluid, such as gas, from the wound via the inlet 252.The pump assembly 230 comprises a USB access door 256 configured toallow access to one or more USB ports. In some embodiments, the USBaccess door is omitted and USB ports are accessed through the door 234.The pump assembly 230 can include additional access doors configured toallow access to additional serial, parallel, and/or hybrid data transferinterfaces, such as SD, Compact Disc (CD), END, FireWire, Thunderbolt,PCI Express, and the like. In other embodiments, one or more of theseadditional ports are accessed through the door 234.

Additional description of the pump assembly is disclosed in U.S. PatentApplication Publication No. 2015/0025482, which is incorporated byreference in its entirety.

Electronics and Software

FIG. 3 illustrates an electrical component schematic 300 of a pumpassembly, such as the pump assembly 230, according to some embodiments.Electrical components can operate to accept user input, provide outputto the user, operate the pump assembly and the TNP system, providenetwork connectivity, and so on. Electrical components can be mounted onone or more printed circuit boards (PCBs). As is illustrated, the pumpassembly can include multiple processors. It may be advantageous toutilize multiple processors in order to allocate or assign various tasksto different processors. A first processor can be responsible for useractivity and a second processor can be responsible for controlling thepump. This way, the activity of controlling the pump, which maynecessitate a higher level of responsiveness (corresponding to higherrisk level), can be offloaded to a dedicated processor and, thereby,will not be interrupted by user interface tasks, which may take longerto complete because of interactions with the user.

The pump assembly can comprise a user interface processor or controller310 configured to operate one or more components for accepting userinput and providing output to the user, such as the display 206, buttons212, etc. Input, to the pump assembly and output from the pump assemblycan controlled by an input/output (I/O) module 320. For example, the I/Omodule can receive data from one or more ports, such as serial,parallel, hybrid ports, and the like. The processor 310 also receivesdata from and provides data to one or more expansion modules 360, suchas one or more USB ports, SD ports, Compact Disc (CD) drives, DVDdrives, FireWire ports, Thunderbolt ports, PCI Express ports, and thelike. The processor 310, along with other controllers or processors,stores data in one or more memory modules 350, which can be internaland/or external to the processor 310. Any suitable type of memory can beused, including volatile and/or non-volatile memory, such as RAM, ROM,magnetic memory, solid-state memory, Magnetoresistive random-accessmemory (MRAM), and the like.

The pump assembly can further comprise a power monitor 325 configured todetermine data regarding the power source (such as a battery) of thepump assembly. The power monitor 325 can be configured to determinebattery status based on data received from one or more hardwarecomponents, such as a battery gas gauge circuit. For example, the powermonitor 325 can be configured to determine remaining battery capacity asa percentage of the total battery capacity based on data received fromthe battery gas gauge circuit. The power monitor 325 alone or incombination with one or more processors disclosed herein can also beconfigured to determine the remaining use time of the pump assembly. Insome embodiments, this is performed by determining the current loadconditions and dividing the current battery capacity by the current loadconditions to determine the remaining use time. The current loadconditions can be determined, for example, based on power used by thepump assembly at a point of time or over a period of time. For instance,current used by the pump assembly can be averaged over a period of timeto obtain the current load conditions. As an example, suppose that theaverage current drawn over the pump assembly over one minute is Xamperes, and that the remaining batter capacity is Y amperes. In thisexample, the remaining usage time is Y/X minutes.

In some embodiments, the power monitor 325 alone or in combination withone or more processors disclosed herein is configured to indicate ortrigger a low battery alarm when it has been determined that theremaining usage time satisfies a low battery condition. For example, thelow battery condition can be a certain duration of remaining usage time,such as 30 minutes, 1 hour, 2 hours, and the like. The power monitor 325alone or in combination with one or more processors disclosed herein canalso be configured to indicate or trigger a critical low battery alarmwhen it has been determined that the remaining usage time satisfies acritical low battery condition. For example, the critical batterycondition can be a certain duration of remaining usage time, such a 5minutes, 10 minutes, 20 minutes, 1 hour, and the like. The pump assemblycan be configured to power off or shut down when it has been determinedthat the remaining usage time satisfies a battery depleted condition,which can be a certain duration of remaining usage time, such as 1minute, 5 minutes, 10 minutes, 12 minutes, and the like. This way, agraceful shut down can be performed before the battery becomes fullydepleted. Graceful shutdown can include stopping therapy, saving data,and the like.

In some embodiments, the power monitor 325 can be configured todetermine, such as based on data received data from one or more hardwarecomponents, the charging status of the battery as well as whether abattery failure has occurred. The power monitor 325 can be configured toreceive data from, for example, a battery charging circuit to determinewhether the battery is actively charging. Further, the power monitor 325can be configured to receive data from a battery gas gauge circuit todetermine if there has been a battery failure. In some embodiments, thepower monitor 325 can be configured to indicate or trigger a devicetechnical failure alarm when it has determined that the battery hasfailed.

In some embodiments, the processor 310 can be a general purposecontroller, such as a low-power processor. In other embodiments, theprocessor 310 can be an application specific processor. The processor310 can be configured as a “central” processor in the electronicarchitecture of the pump assembly, and the processor 310 can coordinatethe activity of other processors, such as a pump control processor 370,communications processor 330, and one or more additional processors 380(e.g., processor for controlling the display 206, processor forcontrolling the buttons 212, etc.). The processor 310 can run a suitableoperating system, such as a Linux, Windows CE, VxWorks, etc.

The pump control processor 370 can be configured to control theoperation of a negative pressure pump 390. The pump 390 can be asuitable pump, such as a diaphragm pump, peristaltic pump, rotary pump,rotary vane pump, scroll pump, screw pump, liquid ring pump, diaphragmpump operated by a piezoelectric transducer, voice coil pump, and thelike. The pump control processor 370 can measure pressure in a fluidflow path, using data received from one or more pressure sensors,calculate the rate of fluid flow, and control the pump. The pump controlprocessor 370 can control pump motor so that a desired level of negativepressure is achieved in the wound cavity 110. The desired level ofnegative pressure can be pressure set or selected by the user. Invarious embodiments, the pump control processor 371 controls the pump(e.g., pump motor) using pulse-width modulation (PWM). A control signalfor driving the pump can be a 0-100% duty cycle PWM signal. The pumpcontrol processor 370 can perform flow rate calculations and detectvarious conditions in a flow path. The pump control processor 370 cancommunicate information to the processor 310. The pump control processor370 can include internal memory and/or can utilize memory 350. The pumpcontrol processor 370 can be a low-power processor.

A communications processor 330 can be configured to provide wired and/orwireless connectivity. The communications processor 330 can utilize oneor more antennas 340 for sending and receiving data. The communicationsprocessor 330 can provide one or more of the following types ofconnections: Global Positioning System (GPS) technology, cellularconnectivity (e.g., 2G, 3G, LTE, 4G), WiFi connectivity. Internetconnectivity, and the like. Connectivity can be used for variousactivities, such as pump assembly location tracking, asset tracking,compliance monitoring, remote selection, uploading of logs, alarms, andother operational data, and adjustment of therapy settings, upgrading ofsoftware and/or firmware, and the like. The communications processor 330can provide dual GPS/cellular functionality. Cellular functionality can,for example, be 3G functionality. In such cases, if the GPS module isnot able to establish satellite connection due to various factorsincluding atmospheric conditions, building or terrain interference,satellite geometry, and so on, the device location can be determinedusing the 3G network connection, such as by using cell identification,triangulation, forward link timing, and the like. The pump assembly caninclude a SIM card, and SIM-based positional information can beobtained.

The communications processor 330 can communicate information to theprocessor 310. The communications processor 330 can include internalmemory and/or can utilize memory 350. The communications processor 330can be a low-power processor.

In some embodiments, the pump assembly can track and store various data,such as one or more of positioning data, therapy parameters, logs,device data, and so on. The pump assembly can track and log therapy andother operational data. Data can be stored, for example, in the memory350.

In some embodiments, using the connectivity provided by thecommunications processor 330, the device can upload any of the datastored, maintained, and/or tracked by the pump assembly. For example,the following information can be uploaded to a remote computer orserver: activity log(s), which includes therapy delivery information,such as therapy duration, alarm log(s), which includes alarm type andtime of occurrence; error log, which includes internal errorinformation, transmission errors, and the like; therapy durationinformation, which can be computed hourly, daily, and the like; totaltherapy time, which includes therapy duration from first applying aparticular therapy program or programs; lifetime therapy information;device information, such as the serial number, software version, batterylevel, etc.; device location information; patient information; and soon. The device can also download various operational data, such astherapy selection and parameters, firmware and software patches andupgrades, and the like. The pump assembly can provide Internet browsingfunctionality using one or more browser programs, mail programs,application software (e.g., apps), etc.

In some embodiments, the communications processor 330 can use theantenna 340 to communicate a location of the pump assembly, such as alocation of a housing of the pump assembly, to other devices in theproximity (for example, within 10, 20, or 50 meters and the like) of thepump assembly. The communications processor 330 can perform one-way ortwo-way communication with the other devices depending on theimplementation. The communications transmitted by the communicationsprocessor 330 can include identifying information to uniquely identifythe pump assembly relative to one or more other pump assemblies also inthe proximity of the pump assembly. For example, identifying informationcan include a serial number or a value derived from the serial number.The signal strength of the transmitted communications by thecommunications processor 330 can be controlled (for example, maintainedat a constant or substantially constant level) to enable another deviceto determine a distance to the pump assembly, such as a distance betweenthe device and the pump assembly.

In some embodiments, the communications processor 330 can communicatewith other devices in the proximity of the pump assembly so that thecommunications processor 330 can itself determine a distance from thepump assembly to the other devices. The communications processor 330, insuch embodiments, can track and store the distance from the pumpassembly to the other devices or indications of change in the distanceover time, and the communications processor 330 can later provide thisinformation to the other devices. For instance, the communicationsprocessor 330 can determine a duration of time during which the pumpassembly has been removed from a coverage area of a device andsubsequently report this time to the device upon being returned to thecoverage area.

FIG. 4 illustrates a firmware and/or software diagram 400 according tosome embodiments. A pump assembly 420 includes a user interfaceprocessor firmware and/or software 422, which can be executed by theuser interface processor 310, pump control processor firmware and/orsoftware 424, which can be executed by the pump control processor 370,communications processor firmware and/or software 426, which can beexecuted by the communications processor 330, and additionalprocessor(s) firmware and/or software 428, which can be executed by oneor more additional processors 380. The pump assembly 420 can beconnected to a computer 410, which can be a laptop, desktop, tablet,smartphone, and the like. A wired or wireless connection can be utilizedto connect the computer 410 to the pump assembly 420. For example, a USBconnection can be used. The connection between the computer 410 and thepump assembly 420 can be used for various activities, such as pumpassembly location tracking, asset tracking, compliance monitoring,selection, uploading of logs, alarms, and other operational data, andadjustment of therapy settings, upgrading of software and/or firmware,and the like. The pump assembly 420 and computer 410 can communicatewith a remote computer or server 440 via the cloud 430. The remotecomputer 440 can include a data storage module 442 and a web interface444 for accessing the remote computer.

The connection between the computer 410 and pump assembly 420 can beutilized to perform one or more of the following: initialization andprogramming of the pump assembly 420, firmware and/or software upgrades,maintenance and troubleshooting, selecting and adjusting therapyparameters, and the like. In some embodiments, the computer 410 canexecute an application program for communicating the pump assembly 420.

In some embodiments, the pump assembly 420 keeps track of a maintenanceschedule and provides an indication (such as message, indicator, oralarm screen as described below) when maintenance is due or past due.For example, maintenance can be performed once a year, and the pumpassembly 420 can provide an indication when a year from the lastperformed maintenance has elapsed. This indication can be provided whenthe pump assembly boots up or at any other suitable time. Information onduration of time before next maintenance is due can also be provided,for example, on the user interface under device information menu (seeFIG. 5E).

The pump assembly 420 can upload various data to the remote computer (ormultiple remote computers) 440 via the cloud 430. As explained above,upload data can include activity log(s), alarm log(s), therapy durationinformation, total therapy time, lifetime therapy information, deviceinformation, device location information, patient information, etc. Inaddition, the pump assembly 420 can receive and process commandsreceived from the cloud 430.

Operation of the Pump Assembly

In some embodiments, the pump assembly 230 can be operated using atouchscreen interface displayed on the screen 206. Various graphicaluser interface (GUI) screens present information on systems settings andoperations, among other things. The touchscreen interface can beactuated or operated by a finger (or a stylus or another suitabledevice). Tapping a touchscreen cam result in making a selection. Toscroll, a user can touch screen and hold and drag to view theselections. Additional or alternative ways to operate the touchscreeninterface can be implemented, such as multiple finger swipes forscrolling, multiple finger pinch for zooming, and the like.

FIGS. 5A-5I illustrate graphical user interface screens according tosome embodiments. The GUI screens can be displayed on the screen 206,which can be configured as a touchscreen interface. Informationdisplayed on the screens can be generated based on input received fromthe user. The GUI screens can be utilized for initializing the device,selecting and adjusting therapy settings, monitoring device operation,uploading data to the network (e.g., cloud), and the like. Theillustrated GUI screens can be generated directly by an operating systemrunning on the processor 310 and/or by a graphical user interface layeror component running on the operating system. For instance, the screenscan be developed using Qt framework available from Digia.

FIG. 5A illustrates a therapy settings screen 500A according to someembodiments. The therapy settings screen 500A can be displayed after thepump assembly has been initialized (e.g., screen 500A can function as ahome screen). The therapy settings screen 500A includes a status bar 502that comprises icons indicating operational parameters of the device.Animated icon 503 is a therapy delivery indicator. When therapy is notbeing delivered, icon 503 can be static and displayed in a color, suchas gray. When therapy is being delivered, icon 503 can turn a differentcolor, such as orange, and becomes animated, such as, rotates, pulsates,become filled with color (see FIG. 5C), etc. Other status bar iconsinclude a volume indicator and a battery indicator, and may includeadditional icons, such as wireless connectivity. The therapy settingsscreen 500A includes date/time and information. The therapy settingsscreen 500A includes a menu 510 that comprises menu items 512 foraccessing device settings, 514 for accessing logs, 516 for accessinghelp, and 518 (see, for example, FIGS. 5C and 5E) for returning to thetherapy settings screen (or home screen) from other screens. The pumpassembly can be configured so that after a period of inactivity, such asnot receiving input from the user, therapy settings screen 500A (or homescreen) is displayed. Additional or alternative controls, indicators,messages, icons, and the like can be used.

The therapy settings screen 500A includes negative pressure up and downcontrols 522 and 524. Up and down controls 522 and 524 can be configuredto adjust the negative pressure setpoint by a suitable step size, suchas ±5 mmHg. As is indicated by label 526, the current therapy selectionis −80 mmHg (or 80 mmHg below atmospheric pressure). The therapysettings screen 500A includes continuous/intermittent therapy selection530. Continuous therapy selection screen can be accessed via control 532and intermittent therapy selection screen can be accessed via control534. As is illustrated, the current therapy setting is to continuouslydeliver negative pressure at −80 mmHg. As is indicated by message 528,therapy delivery can be initiated by pressing a button, such as button212 b on the pump assembly 230. The therapy settings screen 500Aincludes Y-connector selection 535 for treating multiple wounds, such astwo, three, etc. wounds, with one pump assembly 230. Control 536 selectstreatment of a single wound, and control 538 selects treatment of morethan one wound by the pump assembly. As is indicated by the label“Y-CONNECT OFF,” the current selection is to treat a single wound.Additional or alternative controls, indicators, messages, icons, and thelike can be used.

FIG. 5B illustrates therapy settings screen 500B for deliveringintermittent therapy according to some embodiments. Screen 500C can beaccessed via control 534. Therapy settings screen 500B includesintermittent therapy settings 540 and 545. As is illustrated by settingsof controls 542, 544, 546, and 548, respectively, current therapyselection is applying −80 mmHg of reduced pressure for 5 minutesfollowed by 2 minutes of applying atmospheric pressure (or turning offthe vacuum pump). Such treatment cycles can be repeated until stopped bythe user or by the pump assembly 230. Negative pressure levels and timedurations can be adjusted by selecting one or more of controls 542, 544,546, and 548 and operating the up or down controls 522 or 524 untildesired values are selected. In some implementations, more than twonegative pressure values and corresponding durations can be selected fortreatment of a wound. For example, a user can select three or morenegative pressure values and corresponding durations. Additional oralternative controls, indicators, messages, icons, and the like can beused.

FIG. 5C illustrates therapy delivery screen 500C according to someembodiments. Screen 500C can be accessed by selecting desired therapysettings on the screen 500A or 500B and initiating therapy, such as bypressing the button 212 b. As is illustrated, label 552 (“DeliveringTherapy”) indicates that continuous therapy at −120 mmHg of reducedpressure (label 560) is being delivered to a wound. Animated icon 503indicates that therapy is being delivered by cycling though ananimation. As is illustrated in FIGS. 5C and 5D, icon 503 is an energyburst having multiple petals, and the animation sequences through thepetals becoming filled with orange color. Any other suitable animationor combination of animations can be used. Message 529 indicates thattherapy settings can be stopped or paused by pressing a button, such asbutton 212 b, on the pump assembly 230. Menu item 518 can be configuredto return to the therapy settings screen (or home screen) 500A.Additional or alternative controls, indicators, messages, icons, and thelike can be used.

FIG. 5D illustrates therapy delivery screen 500D according to someembodiments. Screen 500D can be displayed after the user has selecteddesired therapy settings on the screen 500B and has initiated therapy,such as by pressing button the 212 b. As is illustrated, intermittenttherapy is being delivered to a wound. Label 551 and tinier 554,respectively, indicate that negative pressure of −120 mmHg is beingdelivered to the wound for 5 minutes. Timer 554 can be configured toshow the remaining amount of time, for example, as a number (e.g., “5min”), as a relative amount (e.g., by adjusting the fill of the circle),and a combination of the two. Labels 555 and 556, respectively, indicatethat 0 mmHg (or atmospheric pressure) is scheduled to be delivered tothe wound for duration of 2 minutes upon expiration of the time period(e.g., 5 minutes) for delivering the first amount of negative pressure(e.g., −120 mmHg). Message 553 (“Leak Check”) indicates that the pumpassembly 230 is performing a leak check. As is further explained below,the pump assembly 230 can perform a leak check when it initiatesdelivery of negative pressure therapy to determine if the fluid flowpath is sufficiently free of leaks (e.g., is properly scaled). Once ithas been determined that no significant leaks are present, message 553can indicate this fact to the user, such as by displaying the message“Seal Achieved.” Menu item 518 can be configured to return to thetherapy settings screen (or home screen). Additional or alternativecontrols, indicators, messages, icons, and the like can be used.

FIG. 5E illustrates settings screen 500E according to some embodiments.The settings screen 500E can be accessed by selecting menu item 512(e.g., from screen 500A or 500B). As is illustrated, settings screen500E includes a menu 560 for adjusting various operational parameters ofthe pump assembly 230, including alarm volume setting, compressionsetting 562, user mode setting (e.g., clinician or patient), languagesetting, time zone setting, flow meter 564, restore presets (e.g.,factory presets), and device information. Attempting to set the usermode as clinician mode may prompt the user to enter a password orsatisfy any other suitable security check. Operating the pump assemblyin clinician mode can provide unrestricted access to all features andsettings, whereas operating the pump assembly in patient mode canprevent inadvertent changes to therapy settings by preventing access toone or more features and settings, such as therapy settings, compressionsettings, and the like. Alternative or additional menu items can bedisplayed. The illustrated menu 560 is an expanded version of the menushowing all menu items. In use, menu 560 may only partially fit on thescreen, and the menu items can be accessed via the scroll bar 561 or viaany other suitable alternative or additional controls. Additional oralternative controls, indicators, messages, icons, and the like can beused.

FIG. 5F illustrates compression settings screen 500F according to someembodiments. The screen 500F can be accessed by selecting the menu item562. The screen 500F includes three compression settings selections: low572, medium 574, and high 576. As is explained below, these selectionscontrol the time it takes to reach a desired or set vacuum level at thewound so that the change in vacuum pressure is gradual. Compression maybe defined as the maximum change (either increase or decrease) innegative pressure per unit time. For example, selecting a highcompression 576 will result in the most rapid achievement of morenegative or more positive pressure under the dressing. Menu item 519 canbe configured to return to the settings screen 500E. In certainembodiments, compression settings screen 500E may be accessed only ifclinician mode has been previously selected. A clinician may selectappropriate compression setting based on one or more physiologicalparameters, such as wound type, patient's age, physical condition, etc.Additional compression settings, such as very low, very high, and thelike can be provided. Additional or alternative controls, indicators,messages, icons, and the like can be used.

FIG. 5G illustrates flow meter screen 500C according to someembodiments. The screen 500G can be accessed by selecting the menu item564 in FIG. 5E. The screen 500G can visually depict the determined orcalculated rate of air (or gas) flow in the fluid flow path, which caninclude the therapy unit assembly, wound dressing, and tubing connectingthe therapy unit assembly to the wound dressing. The screen 500Gillustrates a gauge 580 that visually depicts the determined flow rateand can be used for detection of one or more leaks in the fluid flowpath. Other controls for depicting the flow rate can be alternatively oradditionally used, such as horizontal or vertical bars, digital gauges,labels, and the like.

As is illustrated, the gauge 580 includes a dial 584 with markings 581indicating absence of leaks or a very small leak (positioned at thebeginning of the dial), 582 indicating medium leak (positioned at themiddle of the dial), and 583 indicating high leak (positioned at the endof the dial). The gauge 580 also includes a needle 585 that indicatesthe determined leak rate on the dial 584. The dial 584 can be configuredto be filled in various colors that visually indicate the leak rate. Forexample, green color can indicate a low level leak, yellow color canindicate a higher level (or significant) leak, and red color canindicate a leak of a high level. As is depicted by the position of theneedle 585 being between the marking 582 (middle of the dial) and 583(end or maximum setting of the dial), a fairly severe leak has beendetected. The gauge 580 can assist a user in locating leaks. Othercontrols for depicting the leak rate can be alternatively oradditionally used, such as horizontal or vertical bars, digital gauges,labels, and the like.

FIG. 5H illustrates flow meter screen 500H according to someembodiments. In contrast with the screen 500G, screen 500H illustrates alower detected leak. This is depicted by the needle 585 being positionedcloser to the marking 581 (e.g., needle 585 is to the left of marking582). In some embodiments, detection of leaks exceeding a certainthreshold may trigger an alarm. That is, in the event of a low vacuumlevel at the wound (e.g., due to high leak), the flow meter screen 500Ccan be displayed to help locate the leak (or leaks) in the fluid flowpath. Flow meter screen 500G or 500H can be displayed while therapy isbeing delivered by the pump assembly, as is illustrated by the animatedicon 503.

FIG. 5I illustrates alarms and troubleshooting screen 500I according tosome embodiments. The screen 500I can be accessed by selecting the menuitem 516 for accessing help (see FIG. 5E) and selecting alarms menu itemfrom the help screen (not shown). As is illustrated, screen 500Iincludes a menu 588 with menu items for various alarm andtroubleshooting categories, including over vacuum, high vacuum,blockage, canister flow, high flow/leak, and low or insufficient vacuum(as explained below) as well as technical failure (e.g., unrecoverableerror), battery (e.g., low battery, critical low battery, batteryfailed), and inactivity (e.g., pump assembly is powered on an has beenleft without user interaction for longer than a certain period of time,such as 15 minutes). Alternative or additional menu items can bedisplayed. Accessing a particular menu item can bring up a screen withstep-by-step instructions to assist in resolving the correspondingalarm. The instructions can include a combination of text, audio, video,etc. The illustrated menu 588 is an expanded version of the menu showingall menu items. In use, menu 588 may only partially fit on the screen,and menu items can be accessed via the scroll bar 587 or via any othersuitable alternative or additional controls. Additional or alternativecontrols, indicators, messages, icons, and the like can be used.

FIGS. 6A-6G illustrate alarm screens according to some embodiments. Theillustrated screens can be displayed in response to a condition or setof conditions detected by the pump assembly in order to alert the user.In the event of an alarm, for example, the therapy unit can perform oneor more of the following: sound an audible alarm, display an alarmscreen, illuminate the indicator 204 in a specific color, such asyellow. The therapy unit can be configured to stop or suspend deliveringtherapy in the occurrence of an over vacuum or high vacuum alarm. Ifoccurrence of other alarms is detected, the therapy unit can continuedelivery of therapy.

In some embodiments, the therapy unit can be configured to continuouslymonitor for or check for one or more conditions that may trigger analarm. However, as explained further below, the therapy can be furtherconfigured to suspend detection of some or all of the conditions andsuppress one or more alarm during certain states associated withdelivery of negative pressure.

FIG. 6A illustrates a blockage alarm screen 600A according to someembodiments. Indicator 601 indicates alarm condition. Label 602 is adescription of the alarm (e.g., “WARNING BLOCKAGE”). Icon 603 isconfigured to return the home screen, such as screen 500A. Labels 604and 605 respectively provide information about current therapy settings.As is illustrated, continuous therapy at −25 mmHg of reduced pressure isbeing applied to a wound. Label 606 provides suggested action to correctthe alarm (e.g., “Tubing or canister may be blocked”). Icon 607 isconfigured to bring up alarms and troubleshooting screen 500I in casethe user desires more detailed information regarding the alarms andtroubleshooting. Icon 608 is configured to silence the alarm permanentlyor temporarily. For some alarms, such as non-critical alarms, audibletones can be temporarily silenced by selecting icon 608. If the audiblealarm has been temporarily silenced and a new alarm occurs, the audiblealarm for the new alarm may sound and the new alarm may be displayed.When multiple alarm messages are present, the therapy assembly canalternate between the alarm screens.

Blockage alarm screen 600A can indicate detection of a blockage in theflow path, such as in a conduit connecting the canister (or pump in acanisterless system) with the wound dressing. The alarm may be resolvedby clearing the blockage. The pump assembly may continue to attempt toprovide desired therapy to the wound after blockage has been detected.FIG. 6B illustrates an over vacuum alarm screen 600B according to someembodiments. As is illustrated, the description of the alarm is “OVERVACUUM,” and suggested action to correct the alarm is “Power Off/PowerOn to clear.” This alarm screen can indicate that the therapy unit hasdetected an excessively high vacuum in the fluid flow path (e.g.,exceeding −235 mmHg or any other suitable value), potentially due todevice malfunction. The pump assembly can be configured to stop orsuspend delivering therapy until the over vacuum condition has beencorrected. An audible alarm can be generated, which may not be paused(hence the icon 608 is not displayed in the screen 600B). As suggested,the alarm may be resolved by power cycling the pump assembly.

FIG. 6C illustrates a high vacuum alarm screen 600C according to someembodiments. As is illustrated, the description of the alarm is “HIGHVACUUM,” and suggested action to correct the alarm is “Power Off/PowerOn to clear.” This alarm screen can indicate that the therapy unit hasdetected a high vacuum condition (e.g., exceeding −15 mmHg above thetherapy setpoint or any other suitable value), potentially due to ablockage or device malfunction. The pump assembly can be configured tostop or suspend delivering therapy until the high vacuum condition hasbeen corrected. An audible alarm can be generated, which may not bepaused (hence the icon 608 is not displayed in the screen 600C). Assuggested, the alarm may be resolved by power cycling the pump assembly.

FIG. 6D illustrates a canister full alarm screen 600D according to someembodiments. As is illustrated, the description of the alarm is“CANISTER FULL” because it has been detected that the canister is fullor the internal canister filter is covered with fluid. The alarm may beresolved by replacing the canister. The pump assembly may continue toattempt to provide desired therapy to the wound. The alarm may besilenced. In some systems, such as in canisterless systems where adressing is configured to absorb fluid removed from the wound, dressingfull condition or dressing filter occluded condition can be detected andindicated in a manner similar to the canister full condition.

FIG. 6E illustrates a low vacuum alarm screen 600E according to someembodiments. As is illustrated, the description of the alarm is “LOWVACUUM” because the detected pressure at the wound is lower than thedesired negative pressure by a threshold amount, such as −15 mmHg oranother suitable value. Additionally or alternatively, low vacuumcondition can be detected if there is a leak in the fluid flow path thatpersists for longer than threshold duration, such as 30 seconds or anyother suitable value. The alarm may be resolved by checking theconnections in the fluid flow path for leaks or checking the dressingfor leaks. The pump assembly may continue to attempt to provide desiredtherapy to the wound. In some embodiments, the gauge 580 may bedisplayed on the screen 600E, as is explained below in connection withFIG. 6F. The alarm may be silenced.

FIG. 6F illustrates a leak alarm screen 600F according to someembodiments. As is illustrated, the description of the alarm is “LEAK”because a significant leak (e.g., a leak that exceeds a certainthreshold leak rate) has been detected for a threshold duration, such asfor longer than 2 minutes or any other suitable value. As isillustrated, the leak alarm screen 600F includes the gauge 580illustrating the leak rate detected in the fluid flow path. As isillustrated by the position of the needle 585, a high flow leak has beendetected, which has triggered the leak alarm. The alarm may be resolvedby checking the connections in the fluid flow path for leaks or checkingthe dressing for leaks. The gauge 580, which illustrates the detectedleak rate, can assist in identifying and resolving leaks. The pumpassembly may continue to attempt to provide desired therapy to thewound. The alarm may be silenced.

FIG. 6G illustrates an alarm resolved screen 600E according to someembodiments. Screen 600G can be displayed upon resolution of alarmsdetected by the therapy unit. Screen 600G can be displayed for a periodof time and then be replaced by a therapy deliver screen. The alarm maybe silenced.

Any of the screens depicted in FIGS. 6A-6G may include additional oralternative controls, indicators, messages, icons, and the like. In someembodiments, additional or alternative screens may be used for alertingthe user to one or more alarms.

Delivery of Negative Pressure Wound Therapy

In some embodiments, the pump assembly controls the vacuum pump todeliver negative pressure therapy to a wound according to a selected orprogrammed protocol. Pump control can be performed by the pump controlprocessor 370 alone or in combination with the processor 310. Forexample, as explained above, the user can select continuous operation ata desired pressure (or negative pressure setpoint). The pump assemblycan activate the vacuum pump to reduce or draw down the pressure at thewound (e.g., under the dressing) to reach the setpoint. As explainedbelow, the drawdown can be performed by increasing the negative pressureat the wound limited by a maximum change in negative pressure per unittime called compression, until the setpoint (or another selectedpressure value as explained below) has been achieved. Wound drawdown canbe defined as the period of time immediately after therapy has beeninitiated during which the wound has not yet achieved the setpoint. Asexplained below, at the end of this period when the setpoint isachieved, the flow rate in the fluid flow path should be below a leak(or high flow) threshold and above a low vacuum threshold, otherwise anappropriate alarm will be activated. As another example, the user canselect intermittent operation between two desired pressures (or high andlow pressure setpoints). The pump assembly can activate the vacuum pumpto reduce or draw down the pressure at the wound to reach the highsetpoint. Subsequently, the pump assembly can allow pressure at thewound to increase to reach the low setpoint. As explained below,decreasing and increasing negative pressure can be performed inaccordance with the compression setting. As yet another example,compression can be used anytime there is a change in the pressuresetpoint (which can include stopping delivery of negative pressure). Insome embodiments, different compression settings can be used forsetpoint changes that result in decreasing or increasing pressure at thewound. In various embodiments, compression setting can be adjusted whilea pressure setpoint is being achieved.

FIG. 7 illustrates a process 700 for providing negative pressure woundtherapy according to some embodiments. The process 700 can be executedby the pump control processor 370 alone or in combination with theprocessor 310. The process 700 can be periodically executed, such as forexample every 100 milliseconds (or 10 times per second) or at any othersuitable frequency. Alternatively or additionally, the process 700 canbe continuously executed.

The process 700 can begin in block 702, which it can transition to whentherapy is initiated or when the setpoint is changed while therapy isbeing delivered. In block 702, the process 700 compares wound pressure,which can be determined as explained below, to the setpoint. Forexample, the process 700 can subtract the wound pressure from thesetpoint or vice versa. If the wound pressure is below the setpoint, theprocess 700 can transition to block 704. Conversely, if the woundpressure exceeds or is equal to the setpoint, the process 700 cantransition to block 706.

In block 704 (pressure ramp up), the process 700 can increment a pumpramp setpoint by an amount that depends on the compression setting asexplained below. The vacuum pump will then attempt to draw down (or makemore negative) the wound pressure to reach the current value of the pumpramp setpoint. For example, a suitable pump drive signal, such asvoltage or current signal, can be generated and supplied to the pumpmotor so as to increase the speed of the pump motor to achieve wounddraw down. For purposes of efficiency, the pump motor can be drivenusing PWM or any other suitable method. The process 700 can continueincrementing the pump ramp setpoint until it reaches the setpointselected by the user. The process 700 can transition to block 708 whenthe wound pressure has nearly reached or reached the setpoint, which cancorrespond to reaching steady state pressure under the wound dressing.For example, the process 700 can transition to block 708 when the woundpressure is within a ramp up threshold pressure of the setpoint, such aswithin 2 mmHg of the setpoint or within any other suitable value. Insome embodiments, the pump ramp setpoint can be adaptively set to ahigher negative pressure than the setpoint. For example, as is explainedbelow, the device can detect presence of one or more leaks which resultin a higher level of flow. Because this can cause loss of pressure atthe wound, the device can compensate such loss of pressure by increasingthe pump ramp setpoint above the setpoint. For instance, the device canset the pump ramp setpoint to be 1%, 2%, 5%, etc. more negative than thesetpoint. In certain embodiments, the pump ramp setpoint can beadaptively set to a lower negative pressure (or more positive pressure)than the setpoint.

In block 706 (pressure ramp down), the process 700 can set the pump rampsetpoint to the setpoint selected by the user (or to another set valueas explained above). The process 700 can deactivate the pump so that thewound pressure is allowed to decay, such as due to one or more leaks inthe fluid flow path, to reach or almost reach the setpoint. This can beperformed in accordance with the compression setting, such as forexample, deactivating the pump for a first period of time and thenactivating the pump for a second period of time so that pressure at thewound increases according to the compression setting.

Additionally or alternatively, the process 700 can open and close one ormore valves positioned in the fluid flow path to thereby admit ambientair or another gas into the fluid flow path in order to reach or almostreach the setpoint. This can be performed in accordance with thecompression setting, such as for example, opening the one or more valvesfor a first period of time and then closing some or all of the one ormore valves for a second period of time so that pressure at the woundincreases according to the compression setting. Further, the process 700can operate a positive pressure pump to increase the pressure at thewound. Also, the process 700 can utilize a reservoir configured to storeair or gas to increase the pressure at the wound. This is described inmore detail in U.S. Pat. No. 8,366,692, which is incorporated byreference in its entirety.

At this point, the process 700 can transition to block 708. For example,the process 700 can transition to block 708 when the wound pressure iswithin a ramp down threshold pressure of the setpoint, such as within 5mmHg of the setpoint or within any other suitable value. In some cases,the ramp down threshold pressure can be the same as the ramp upthreshold pressure. In some embodiments, the pump ramp setpoint can beadaptively set to a lower negative pressure than the setpoint. Forexample, as is explained below, the device can detect presence of one ormore leaks which result in a higher level of flow. Because this cancause loss of pressure at the wound, the device can compensate such lossof pressure by decreasing the pump ramp setpoint below the setpoint. Forinstance, the device can set the pump ramp setpoint to be 1%, 2%, 5%,etc. less negative than the setpoint. In certain embodiments, the pumpramp setpoint can be adaptively set to a higher negative pressure (ormore positive pressure) than the setpoint.

In block 708 (steady state), the pump ramp setpoint can be set to thesetpoint selected by the user (or another suitable value). The process700 can control the vacuum pump to maintain the desired negativepressure at the wound. One or more conditions, such as high vacuum, lowvacuum, leak, and the like can be detected in block 708 as is explainedbelow. If the user changes the setpoint to be more negative or morepositive or if delivery of therapy is paused, the process 700 cantransition to block 702.

In some embodiments, the pump assembly controls the vacuum pump to drawdown the wound (e.g., as is explained above in connection with block704) by utilizing compression. Using compression can be beneficial foravoiding rapid changes in wound pressure, which can minimize patientdiscomfort, reduce noise produced as a result of operating the pump,maintain efficient delivery of negative pressure, maintain efficient useof power (e.g., battery power), and the like. Compression can beexecuted by the process 700, which in turn can be implemented by thepump control processor 370 alone or in combination with the processor310. Compression can correspond to the maximum desired increase ordecrease in negative pressure at the wound per unit of time. Compressioncan be determined based on the negative pressure setpoint in thecontinuous mode or low and high negative pressure setpoints in theintermittent mode and selected compression setting (e.g., low, medium,or high) as explained above in connection with FIG. 5F.

Compression can be utilized when the wound is expected to experience asignificant increase in negative pressure. This can occur when: (1)therapy is initiated on a deflated wound, and negative pressure willincrease from zero or substantially zero to reach the pressure setpointat the wound; (2) therapy is active in intermittent mode and duringtransitions from a low negative pressure setpoint to a high negativepressure setpoint, negative pressure will increase to reach the highpressure setpoint at the wound; (3) therapy is active in intermittentmode and during transitions from a high negative pressure setpoint to alow negative pressure setpoint, negative pressure will decrease to reachthe low pressure setpoint at the wound; (4) therapy is active and thesetpoint has been changed to a more negative pressure value, which willcause negative pressure to be increased to reach the higher pressuresetpoint at the wound; (5) therapy is active and the setpoint has beenchanged to a more positive pressure value, which will cause negativepressure to be decreased to reach the lower pressure setpoint at thewound; and (6) therapy is active and is stopped or paused for a periodof time, which will cause the pressure to be gradually restored toatmospheric pressure. Additional situations in which compression may beutilized include, for example, when a leak is introduced after seal hasbeen achieved, which can cause negative pressure at the wound to rapidlydrop and the vacuum pump to increase or ramp up delivery of negativepressure in an attempt to maintain pressure. Once the leak has beencorrected, the pump would attempt to rapidly restore setpoint pressureat the wound according to the compression setting.

Compression can be achieved by maintaining a secondary negative pressuresetpoint target that represents the negative pressure setpoint allowedby compression as a function of time. The secondary setpoint cancorrespond to the pump ramp setpoint. Secondary setpoint can beincremented or decremented based on the selected compression setting.Secondary setpoint can be incremented or decremented by a suitableamount every time process 700 is executed, such as 10 times a second orany other suitable frequency. For example, if low compression settinghas been selected, the secondary setpoint can be incremented by −0.6mmHg (or decremented by 0.6 mmHg), which can result in negative pressureramp up (or ramp down) of no more than approximately −8 mmHg (or 8 mmHg)per second (assuming that pump rate is incremented 10 times a second,such as a result of executing the process 700). If medium compressionsetting has been selected, the secondary setpoint can be incremented by−2 mmHg (or decremented by 2 mmHg), which can result in negativepressure ramp up (or ramp down) of no more than approximately −20 mmHg(or 20 mmHg) per second. If high compression setting has been selected,the secondary setpoint can be incremented by −4 mmHg (or decremented by4 mmHg), which can result is negative pressure ramp up (or ramp down) ofno more than approximately −40 mmHg (or 40 mmHg) per second. Thesevalues are illustrative and any other suitable values can be used.

In some embodiments, the pump assembly monitors various parameters, suchas pressure and rate of flow in the fluid flow path, in order to controlthe pump in connection with delivery of negative pressure wound therapy.Parameters monitoring and pump control can be performed by the pumpcontrol processor 370 alone or in combination with the processor 310.Monitoring the flow rate can be used, among other things, to ensure thattherapy is properly delivered to the wound, to detect leakages,blockages, high pressure, and low vacuum, canister full, and the like.

The pump assembly can be configured to indirectly measure the flow ratein the fluid flow path. For example, the pump assembly can measure thespeed (e.g., as frequency) of the vacuum pump motor by using atachometer. Alternatively or additionally, the pump assembly can measurea level of activity or duty cycle of the pump using any suitableapproach, such as by monitoring voltage or current supplied to the pump,sensing pump speed (e.g., by using a Hall sensor), measuring back EMFgenerated by the pump motor, and the like. Tachometer readings can beaveraged in order to mitigate the effects of one or more errantreadings. A number of most recent tachometer readings, such as over last2.5 seconds or any other suitable time period, can be averaged to obtainshort tachometer average. A number of less recent tachometer readings,such as aver the last 30 seconds or any other suitable time period, canbe averaged to obtain long tachometer average. Short and long tachometeraverages can be utilized for pump control. Additionally oralternatively, the pump assembly can directly measure the flow rate,such as by using a flow meter.

Flow rate can be estimated as the air or gas volume moving over thewound per unit of time normalized to standard temperature and standardpressure (e.g., 1 atm). Flow rate can be periodically computed, such asevery 250 milliseconds or any other suitable time value, according tothe following formula:Flow Rate=Slope*Tachometer+Intercept

Tachometer is short tachometer average (e.g., in Hz) and Slope andintercept are constants that are based on the pressure setpoint. Thevalues for Slope and Intercept can be determined for possible pressuresetpoints (e.g., −25 mmHg, −4 mmHg, −50 mmHg, −60 mmHg, −70 mmHg, −80mmHg, −90 mmHg, −100 mmHg, −120 mmHg, −140 mmHg, −160 mmHg, −180 mmHg,−200 mmHg) or a given vacuum pump type. The flow as a function of thepump speed may not be a best fit as a single line because the vacuumpump can be designed to be more efficient at lower flow rates. Becauseof this, slope and intercept values can be pre-computed for varioussetpoints and various pumps, Flow rate can be measured in standardliters per minute (SLPM) or any other suitable measurement unit. Asexplained below, the determined flow rate can be compared to variousflow rate thresholds, such as blockage threshold, leakage threshold, andmaximum flow rate threshold, to determine a presence of a particularcondition, such as a blockage, leakage, over vacuum, etc.

In addition, the pump assembly can determine and monitor pressure in theflow path using one or more sensors. In some embodiments, the pumpassembly includes a pressure sensor in or near the inlet 252 (orcanister connection) of the pump assembly 230. This pressure sensor canmeasure the pressure in the canister (or in or near the dressing in acanisterless system). The arrangement of one or more pressure sensors indisclosed in U.S. Patent Publication No. 201570025482, which isincorporated by reference in its entirety. The pump assembly cancontinuously measure pressure in the canister, such as every millisecondor any other suitable duration. A suitable number of latest pressuresensor readings can be averaged to mitigate the effects of one or moreerrant readings.

Wound pressure can be estimated using the measured canister pressure andthe pump speed. Because of presence of one or more leaks in the flowpath, wound pressure may not be the same as canister pressure. Forexample, wound pressure may be lower or more positive than canisterpressure. In some embodiments, wound pressure is estimated using thefollowing formula:Wound Pressure=Canister Pressure−(Slope*Tachometer+Intercept)

Canister Pressure is averaged measured canister pressure. As explainedabove, Tachometer is short tachometer average and Slope and Interceptare constants that are based on the pressure setpoint. The values forSlope and Intercept are not necessarily same value as used above fordetermining the flow rate. Additionally or alternatively, wound pressurecan be measured directly by a pressure sensor placed in the wound ornear the wound or under the dressing.

Based on the determined flow rate, canister pressure, and wound pressurevalues, the pump assembly can monitor and detect various operatingconditions. One or more of these conditions can be detected by theprocess 700 while the process in in block 708. Blockage in the fluidflow path can be determined by comparing the flow rate, as reflected bylong tachometer average, to a particular blockage threshold over orduring a period of time, such as 2 minutes or any other suitableduration. The blockage threshold can be selected or determined based onthe particular pressure setpoint. That is, to detect blockage, the pumpassembly can utilize a plurality of blockage thresholds corresponding toparticular pressure setpoints. As explained above, the flow rate can beindirectly determined by detecting and monitoring the pump speed. Longtachometer average can be compared to the blockage threshold.Alternatively or additionally, short tachometer average or any othersuitable measure of flow rate can be compared to the blockage threshold.

If the threshold is satisfied during a duration of a period of time, thepump assembly determines that there is a blockage in the fluid flow pathand provides an indication (e.g., alarm screen). For example, todetermine presence of a blockage, the pump assembly can determinewhether the long tachometer average satisfies or exceeds the blockagethreshold during a 2 minute period of time or during any other suitableperiod of time. Because long tachometer average may be updated atperiodic time intervals due to periodic sampling of the tachometer, thepump assembly may compare the long tachometer average as it is beingupdated to the blockage threshold aver the 2 minute period of time.Blockage can be detected provided that each long tachometer averagedetermined during the 2 minute interval satisfies or exceeds theblockage threshold. Alternatively or additionally, blockage can bedetected if the majority of sampled long tachometer averages, such as 9out of 10 or any other suitable number, satisfy or exceed the blockagethreshold. Detected blockage may be cleared when the long tachometeraverage falls below the blockage threshold for a period of time, such as5 seconds or any other suitable duration.

In some embodiments, blockage detection may be suspended while theprocess 700 is in block 706. That is, blockage detection can beconfigured to be suppressed or disabled when the therapy unit is in theramp down state 706. Blockage detection can be enabled or re-enabledwhen the process transitions to another state, such as the steady state708. In some embodiments, blockage detection can be disabled when theprocess 700 is in a state other than the ramp down state 706, such aswhen the process 700 is in the ramp up state 704, and re-enabled whenthe process 700 is in a state other than the steady state 708. In someembodiments, the process 700 can continuously monitor for a blockagecondition, but when such conditions is detected, the process 700 can beconfigured to suppress the blockage alarm when in, for example, apressure ramp down state.

When the pump is off, such as when intermittent therapy is applied withone of the pressure setpoints being set to zero, and negative pressureat the wound is expected to decrease (or become more positive) due toleaks, blockage can be detected by determining whether the pressurelevel at the wound is decreasing or decaying as expected. For example,the drop in pressure at the wound can be computed over a period of time,such as 30 seconds or any other suitable duration. A blockage may bepresent if the wound pressure at the end of the period of time has notdecreased to satisfy (e.g., exceed) a pressure decay threshold.

The pump assembly can detect and provide indication of a low vacuumcondition by determining whether the canister pressure satisfies (e.g.,falls below or is more positive than) a low vacuum pressure thresholdduring a period of time, such as 30 seconds or any other suitableduration. The low vacuum pressure threshold can be selected ordetermined based on the pressure setpoint. As is explained above inconnection with blockage detection, low vacuum detection may besuspended while the process 700 is in block 706. Detected low vacuum canbe cleared when the canister pressure exceeds the low vacuum pressurethreshold for a period of time, such as 5 seconds or any other suitablevalue. Alternatively or additionally, the pump assembly can compare themeasured wound pressure with the low vacuum pressure threshold.

The pump assembly can detect and provide indication of a high vacuumcondition by determining whether the canister pressure satisfies (e.g.,exceeds) a particular high vacuum pressure threshold during a period oftime, such as 30 seconds or any other suitable duration. The high vacuumpressure threshold can be selected or determined based on the pressuresetpoint. As is explained above in connection with blockage detection,high vacuum detection may be suspended while the process 700 is in block706. Detected high vacuum may be cleared by power cycling the pumpassembly or by another other suitable means, such as by determining thatthe canister pressure falls below the high vacuum pressure threshold fora period of time, such as 5 seconds or any other suitable duration.Alternatively or additionally, the pump assembly can compare themeasured wound pressure with the high vacuum pressure threshold.

The pump assembly can detect and provide indication of an over vacuum(or excessive vacuum) condition by determining whether the canisterpressure satisfies (e.g., exceeds) an over vacuum threshold, such as−250 mmHg or any other suitable value, during a period of time, such as2 seconds or any other duration. Detected over vacuum may be cleared bypower cycling the pump assembly or by another other suitable means, suchas by determining that the canister pressure falls below the over vacuumpressure threshold for a period of time, such as 5 seconds or any othersuitable duration. Alternatively or additionally, the pump assembly cancompare the wound pressure with the over vacuum threshold. As isexplained above in connection with blockage detection, detection of overvacuum may be suspended while the process 700 is in block 706.

The pump assembly can detect and provide indication of a leak conditionby determining whether the short tachometer average satisfies a leakthreshold during a period of time, such as 2 minutes or any othersuitable duration. The leak threshold can be selected or determinedbased on the pressure setpoint. For example, the pump assembly candetermine whether the short tachometer average exceeds the leakthreshold over a 2 minute period as the vacuum pump is attempting toreach and/or maintain the desired setpoint in the presence of one ormore leaks. Alternatively or additionally, the pump assembly can comparethe long tachometer average with the leak threshold. As is explainedabove in connection with blockage detection, leak detection may besuspended while the process 700 is in block 706. Detected leak may becleared when the short tachometer average falls below the leak thresholdfor a period of time, such as 5 seconds or any other suitable duration.Alternatively or additionally, long tachometer average or any othersuitable measure of flow rate can be compared to the leak threshold.

The pump assembly can detect and provide indication of a canister fullcondition. This determination can be made in when the process 700 is inblock 708. First, the pump assembly can determine whether the shorttachometer average is below the leak threshold and the canister pressureexceeds (or is more negative than) the low vacuum pressure thresholds isindicated by the short tachometer average being below the leakthreshold, there are leak or leaks in the fluid flow path while there isno tow vacuum condition detected, as is indicated by canister pressurebeing above the low vacuum pressure threshold (e.g., canister pressureis normal). That is, the determination of canister pressure remaining ata normal level while presence of a significant leak in the fluid flowpath has been detected (e.g., as indicated by pump speed being fairlylow), provides an indication that the canister may be full (e.g.,canister filter may be blocked).

After it has been determined that the short tachometer average is belowthe leak threshold and the canister pressure exceeds the low vacuumpressure threshold, determination of Whether the canister if full isperformed based at least in part on measuring characteristics ofpressure pulses or signals in the fluid flow path. During operation, thepump generates pressure pulses or signals that are propagated throughthe fluid flow path. The pressure signals, which can be detected by apressure sensor, are illustrated by the pressure curve 802 of FIG. 8according to some embodiments. As is illustrated in region 804, pressurein the fluid flow path varies or oscillates around a particular pressuresetpoint 808 during normal operation of the system. Region 806illustrates pressure pulses in the flow path in presence of a blockagedistal to the pump. For example, the canister (or dressing) becomes fulland/or a canister (or dressing) filter is occluded or blocked.

As is illustrated in region 806, presence of a distal blockage causes areduced volume to be seen upstream of the canister (or dressing), andthe amplitude of the pressure pulses changes (e.g., increases). Thefrequency of a pressure signal also changes (e.g., slows down ordecreases). Observed changes in one or more parameters of the pressuresignal can be used to identify the type of distal blockage present, suchas distinguish between canister (or dressing) full and other types ofblockages in the fluid flow path. Changes in the amplitude of thepressure signal can be measured using a variety of techniques, such asby measuring peak-to-trough change. In certain embodiments, the changesin the pressure pulse signal can be magnified or enhanced by varying thepump speed, varying the cadence of the pump, such as by adjusting PWMparameters, and the like. Such adjustments of pump operation are notrequired but can be performed over short time duration and the changescan be small such that the operation of the system remains relativelyunaffected. In some systems, such as in canisterless systems where adressing is configured to absorb fluid removed from the wound, detectionof a dressing full condition or dressing filter (which may behydrophobic) occluded condition can be an equivalent to detection ofcanister full condition.

Canister full condition can be detected by collecting a plurality ofpressure sensor readings, each performed over a time duration (e.g., 2seconds or any other suitable duration which may be vary between sampleperiods), are collected. A number of readings of the plurality ofreadings, such as 25 sample periods out of 30 or any other suitablenumber, are checked to determine if each indicates that the canister isfull. This can performed by determining maximum and minimum pressurevalues captured over the time duration of a particular sample period.The values can be voltage values, current values, or any other suitablevalues that correspond to pressure. A difference between maximum andminimum values for a particular sample period corresponds topeak-to-through pressure (which is indicative of change in pressurepulse amplitude). If it is determined that the peak-to-through pressurefor a particular sample period exceeds a threshold pressure value, thenthe particular sample period indicates that the canister is full.

The threshold value can be any suitable pressure threshold, such as avalue selected or determined based on the negative pressure setpoint andthe current level of activity of the pump, which as explained above canbe determined using short tachometer average (or long tachometer averageor any other suitable measure of flow rate). For example, thresholdvalues listed in Table 1 can be used for comparing to peak-to-throughpressure. These values correspond to a particular pump motor andparticular pressure sensor.

TABLE 1 Threshold values for detecting canister full conditionTachometer Frequency Peak-to-Through Pressure Setpoint (in Hz) (in mV)(in mmHg) Low Med High Low Med High  25 17  25  <25  50 110 215  40 23 35  <35  75 135 220  50 30  50  <50  90 175 225  60 30  55  <55  80 185225  70 40  60  <60 115 185 235  80 40  60  <60 100 165 235  90 45  65 <65 110 170 235 100 45  65  <65 105 165 235 120 45  75  <75 105 175 235140 50  85  <85 110 190 235 160 60  90  <90 110 165 220 180 75 100 <100130 165 220 200 75 100 <100 125 155 210

Canister full determination can be performed on a sliding window basis.For example, a sliding window of 25 out of 30 sample periods can beanalyzed and if 25 sample periods are determined to indicate that thecanister is full, the pump concludes that the canister (or dressing) isfull. Assuming that the sample period is 2 seconds, using a slidingwindow of 25 out of 30 sample periods effectively results in determiningwhether change in pressure pulse amplitude exceeds the threshold for 60seconds. If short tachometer average becomes greater than the leakthreshold or canister pressure becomes less than the low vacuum pressurethreshold, canister full detection can be suspended or terminated. Forexample, if a sliding window of 25 out of 30 sample periods with eachsample period having duration of 2 seconds in used, 60 second timer forcanister full detection can be reset when it has been determined thatshort tachometer average becomes greater than the leak threshold orcanister pressure becomes less than the low vacuum pressure threshold.This can prevent generation of unnecessary and undesirable alarms.

Alternatively or additionally, canister full condition can be detectedif a single sample period indicates that the canister is full. However,performing canister full detection using a plurality of sample periodscan mitigate the effects of one or more transient conditions in thefluid flow path or one or more errant pressure readings. Alternativelyor additionally, canister full detection can be performed by measuringthe frequency of detected pressure signal and comparing the measuredfrequency to one or more suitable thresholds. As is explained above inconnection with blockage detection, canister full detection may besuspended.

The pump assembly can perform leak check test, which may result indetection of a leak or low vacuum. If at any point during a time periodthat follows initiation of therapy, such as 45 seconds or any othersuitable duration after therapy has been started, the short tachometeraverage rate falls below the leak threshold and process 700 hastransitioned to block 708 (steady state), the leak check test has passedand suitable seal is deemed to have been achieved. That is, if pressureat the wound has reached the desired setpoint within the period of timeand the flow rate (as indicated by the short tachometer average or anyother suitable metric) does not satisfy or exceed the leak threshold, itis determined that the fluid flow path is suitably scaled and nosignificant leaks are present (e.g., the dressing has been properlyplaced and proper connections between pump assembly, canister, anddressing have been made). However, if the short tachometer averageremains above the leak threshold at the end of the period of time, aleak is likely to be present, and the pump assembly indicates presenceof a leak.

If at the end of the period of time, the process 700 remains in block704 (or 706) and has not transitioned to block 708, the pump assemblydetermines whether the canister pressure satisfies or is above the lowvacuum pressure threshold and the short tachometer average is below theleak threshold. If both of these conditions are met, it is determinedthat the fluid flow path is suitably sealed and no significant leaks arepresent. That is, even though the process 700 has not yet transitionedto block 708, which indicates that the setpoint has been reached orsubstantially reached, the pump is properly working toward establishingthe negative pressure setpoint at the wound as is evidenced by the flowrate remaining below the leak threshold and the vacuum level remainingabove the low vacuum threshold. Conversely, if the flow rate satisfiesor exceeds the leak threshold, a leak is likely to be present, and thepump assembly indicates presence of a leak. If the low vacuum thresholdis satisfied, the pump assembly indicates a low vacuum condition.Alternatively or additionally, long tachometer average or any othersuitable measure of flow rate can be compared to the blockage threshold.

After leak cheek test has passed, a suitable seal can be deemed to havebeen achieved until therapy is paused. After therapy is restarted, leakcheck test can be performed. As is explained above in connection withblockage detection, leak check may be suspended.

In some embodiments, selecting or activating Y-connect feature (see FIG.5A) for treatment of multiple wounds, can alter or modify detection ofone or more conditions, such as blockages, leaks, canister fullcondition, and the like. Activating the Y connect feature can adjust oneor more of various thresholds described above. For example, activatingthe Y-connect feature can decrease sensitivity of blockage detection byincreasing the blockage threshold, which is used for blockage detectionas explained above. The blockage threshold can be increased by asuitable amount, such as doubled.

In additional or alternative embodiments, multiple pressure sensors canbe placed in the fluid flow path to facilitate detection of one or moreof the above-described conditions. For example, in addition to orinstead of the pressure sensor being placed in the pump inlet, apressure sensor can be placed in the wound or under the dressing todirectly determine the wound pressure. Measuring pressure at differentlocations in the fluid flow path, such as in the canister and at thewound, can facilitate detection of blockages, leaks, canister fullcondition, and the like. Multiple lumens can be utilized for connectingfluid flow path elements, such as pressure sensors, canister, pumpassembly, dressing, and the like. Canister full condition can bedetected by placing a sensor, such as capacitive sensor, in thecanister. In some embodiments, in order to prevent occurrence of overvacuum, the maximum pressure supplied by the pump can be limitedmechanically or electrically. For example, a pump drive signal, such asvoltage or current supplied to the pump, can be limited not exceed amaximum flow rate threshold, such as 1.6 liters/min or any othersuitable value. Additional details of flow rate detection and pumpcontrol are provided in U.S. Patent Publication No. 2013/0150813, whichis incorporated by reference in its entirety.

In some embodiments, one or more flow sensors and/or flow meters can beused to directly measure the fluid flow. In some embodiments, the pumpassembly can utilize one or more of the above-described techniques inparallel to control the pump and to detect various conditions. The pumpassembly can be configured to suitably arbitrate between usingparameters determined by different techniques. For example, the pumpassembly can arbitrate between flow rates determined indirectly, such asbased on the pump speed as measured by a tachometer, and directly, suchas by using a flow meter. In certain embodiments, the pump assembly canindirectly determine the flow rate and resort to direct determination ofthe flow rate when needed, such as when indirectly determined flow rateis perceived to be inaccurate or unreliable.

Other Variations

Any value of a threshold, limit, duration, etc. provided herein is notintended to be absolute and, thereby, can be approximate. In addition,any threshold, limit, duration, etc. provided herein can be fixed orvaried either automatically or by a user. Furthermore, as is used hereinrelative terminology such as exceeds, greater than, less than, etc. inrelation to a reference value is intended to also encompass being equalto the reference value. For example, exceeding a reference value that ispositive can encompass being equal to or greater than the referencevalue. In addition, as is used herein relative terminology such asexceeds, greater than, less than, etc. in relation to a reference valueis intended to also encompass an inverse of the disclosed relationship,such as below, less than, greater than, etc. in relations to thereference value.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), and/or all of the steps of any method or process sodisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Theprotection is not restricted to the details of any foregoingembodiments. The protection extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. For example, the actual stepsand/or order of steps taken in the disclosed processes may differ fromthose shown in the figure. Depending on the embodiment, certain of thesteps described above may be removed, others may be added. For instance,the various components illustrated in the figures may be implemented assoftware and/or firmware on a processor, controller, ASIC, FPGA, and/ordedicated hardware. Hardware components, such as processors, ASICs,FPGAs, and the like, can include logic circuitry. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure.

User interface screens illustrated and described herein can includeadditional and/or alternative components. These components can includemenus, lists, buttons, text boxes, labels, radio buttons, scroll bars,sliders, checkboxes, combo boxes, status bars, dialog boxes, windows,and the like. User interface screens can include additional and/oralternative information. Components can be arranged, grouped, displayedin any suitable order.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by diose skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

What is claimed is:
 1. An apparatus for applying negative pressuretherapy to a wound, the apparatus comprising: a source of negativepressure configured to be in fluidic communication with a wound dressingcovering the wound, the source of negative pressure configured toaspirate fluid from the wound via a fluid flow path; a pressure sensorconfigured to measure pressure in the fluid flow path; a controllerprogrammed to operate the source of negative pressure to achieve atarget pressure in the fluid flow path, the controller furtherprogrammed to: determine a pressure difference between a currentpressure in the fluid flow path measured by the pressure sensor and thetarget pressure, the target pressure being more positive than thecurrent pressure; based on the pressure difference and a compressionsetting, determine an intermediate pressure that is more positive thanthe current pressure and more negative than the target pressure; andoperate the source of negative pressure by turning off the source ofnegative pressure for a duration of time to attain the intermediatepressure in the fluid flow path and then operating the source ofnegative pressure to attain the target pressure in the fluid flow path.2. The apparatus of claim 1, wherein the controller is programmed tooperate the source of negative pressure by turning off the source ofnegative pressure for the duration of time to attain the intermediatepressure in the fluid flow path and then activating the source ofnegative pressure to attain the target pressure in the fluid flow path,the duration of time depending on the compression setting.
 3. Theapparatus of claim 1, wherein the controller is further programmed to:determine a pressure increment based on the compression setting; and setthe intermediate pressure to a sum of the current pressure and thepressure increment.
 4. The apparatus of claim 3, wherein the controlleris further programmed to, in response to determining that theintermediate pressure has been attained in the fluid flow path, updatethe intermediate pressure to be equal to a sum of a previousintermediate pressure setting and the pressure increment.
 5. Theapparatus of claim 3, wherein the controller is further programmed to,in response to determining that the intermediate pressure has beenattained in the fluid flow path, redetermine the pressure increment andupdate the intermediate pressure to be equal to a sum of a previousintermediate pressure and the redetermined pressure increment.
 6. Theapparatus of claim 1, wherein the controller is programmed to set thecompression setting according to a user selection.
 7. A method ofoperating a negative pressure apparatus, the method comprising:measuring pressure in a fluid flow path comprising a source of negativepressure configured to be in fluidic communication with a wound dressingcovering a wound; determining a pressure difference between a currentpressure in the fluid flow path and a target pressure, the targetpressure being more positive than the current pressure; based on thepressure difference and a compression setting, determining anintermediate pressure that is more positive than the current pressureand more negative than the target pressure; and operating the source ofnegative pressure by turning off the source of negative pressure for aduration of time to attain the intermediate pressure in the fluid flowpath and then operating the source of negative pressure to attain thetarget pressure in the fluid flow path, wherein the method is performedby a controller.
 8. The method of claim 7, wherein operating the sourceof negative pressure to attain the target pressure in the fluid flowpath comprises activating the source of negative pressure to attain thetarget pressure in the fluid flow path, the duration of time dependingon the compression setting.
 9. The method of claim 7, furthercomprising: determining a pressure increment based on the compressionsetting; and setting the intermediate pressure to a sum of the currentpressure and the pressure increment.
 10. The method of claim 9, furthercomprising in response to determining that the intermediate pressure hasbeen attained in the fluid flow path, updating the intermediate pressureto be equal to a sum of a previous intermediate pressure and thepressure increment.
 11. The method of claim 9, further comprising inresponse to determining that the intermediate pressure has been attainedin the fluid flow path, redetermining the pressure increment andupdating the intermediate pressure to be equal to a sum of a previousintermediate pressure and the redetermined pressure increment.
 12. Themethod of claim 7, further comprising setting the compression settingaccording to a user selection.
 13. The method of claim 12, furthercomprising causing a touch screen display to display a menu configuredto permit a user to select the compression setting.
 14. The method ofclaim 7, wherein turning off the source of negative pressure for theduration of time is performed during a transition from a first negativepressure to a second negative pressure more positive than the firstnegative pressure.
 15. The method of claim 9, wherein determining thepressure increment comprises selecting the pressure increment accordingto the compression setting.
 16. The apparatus of claim 1, wherein thecontroller is programmed to turn off the source of negative pressure forthe duration of time during a transition from a first negative pressureto a second negative pressure more positive than the first negativepressure.
 17. The apparatus of claim 3, wherein the controller isprogrammed to select the pressure increment according to the compressionsetting, and wherein when the compression setting is a first setting,the pressure increment that is selected is smaller than another pressureincrement that is selected by the controller when the compressionsetting is a second setting different from the first setting.
 18. Theapparatus of claim 6, further comprising a touch screen display, andwherein the controller is further programmed to cause the touch screendisplay to display a menu configured to permit a user to select thecompression setting.
 19. The apparatus of claim 1, wherein thecontroller is further programmed to select the compression setting froma plurality of compression settings.
 20. The apparatus of claim 19,wherein the plurality of compression settings comprises a lowcompression setting, a medium compression setting, and a highcompression setting.